They called the assassination a "villainous act" and rejected the claims of Amir's lawyers that a second, unknown gunman shot Rabin, calling the assertions "fictional detective stories."

Amir, a religious Jew, had admitted during his trial that he shot Rabin as he left a Nov. 4 peace rally in Tel Aviv.

He said he intended only to paralyze the Israeli leader. But, Amir added, he was happy when he learned Rabin had died.

Amir sought religious justification for his act, saying that he believed Rabin's peace policies with the Palestinians were endangering Jewish lives.

Amir was not at Sunday's ruling. In a letter to the justices, Amir said he was on a hunger strike to protest his prison conditions and that the journey to the Jerusalem courthouse would be "too taxing."

Amir's sister, Hadas, said, "There is no justice, or attempt to be objective" in the case.

"They gave him the life sentence, but the prison authorities have given him the death sentence," she told Israel Radio.

In March, the Tel Aviv District Court sentenced Amir to life in prison for assassinating Rabin.

Amir is also a defendant in a second trial, along with his brother, Haggai, and a friend, Dror Adani, for plotting to kill Rabin. A verdict in that case is expected in September.

In a separate development, Israeli prison authorities last week discovered electrical cords and other materials that could be used to make explosives in the prison cell of Haggai Amir.

Acting on a tip, prison authorities searched Haggai Amir's cell and found electrical wiring, pages from physics and chemistry textbooks, and sketches of electrical circuits.

Public Security Minister Avigdor Kahalani ordered an investigation into how Amir acquired the materials.

Haggai Amir was arrested a day after his younger brother carried out the assassination.

Investigators later discovered grenades and explosives that Haggai Amir had stockpiled in the family's home.